A stripped down version of Kerbal Space Program for modding purposes. Loads in roughly 10 seconds.
Install: Enter your game's GameData folder, and delete the Squad folder, or (reccomended) move it to somewhere else as a backup. If you have the DLCs, there may also be a SquadExpansion folder - do the same. Then, go to releases and download the zip for the new squad folder and extract it into the GameData folder.
If you want to revert back, simply delete the new squad folder and move back the old one (and SquadExpansion if you have it as well).